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  #1  
Old 10-24-2007, 07:33 PM
Meeko Meeko is offline
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Why does my HD TV programming Pixelate and 'drop dead' ?

I don't know how to explain it. At least not the headline.

We have an HD TV. We have HD programming.

Occasionally, more than we would like, the Audio and Video will stutter and stop.

Most times it happens at the WORST time (that is, durring some part of the show we would actually like to see.)

What is going on here?
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  #2  
Old 10-24-2007, 07:41 PM
KneadToKnow KneadToKnow is online now
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You don't say the source of your HD programming. If it's cable or satellite, my WAG would be that the bandwidth simply gagged. If it's over the air, I got nothin'.
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  #3  
Old 10-24-2007, 07:42 PM
Mr. Slant Mr.  Slant is offline
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That's what happens when a compressed digital signal fails.

If I put my hand in front of a poster you're looking at, you can still see most of the poster.

If I were to delete 1K of data from a 100K JPEG file and then hand the JPEG to your computer, the picture wouldn't come out worth crap.

So, if a digital signal gets messed up, you gets what you're getting.
If an analog signal gets messed up, within limits, it just degrades.

It's analogous to driving a car with TNT and detonators strapped to both bumpers.
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Old 10-24-2007, 08:16 PM
Absolute Absolute is offline
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Quote:
Originally Posted by Mr. Slant
That's what happens when a compressed digital signal fails.

If I put my hand in front of a poster you're looking at, you can still see most of the poster.

If I were to delete 1K of data from a 100K JPEG file and then hand the JPEG to your computer, the picture wouldn't come out worth crap.

So, if a digital signal gets messed up, you gets what you're getting.
If an analog signal gets messed up, within limits, it just degrades.

It's analogous to driving a car with TNT and detonators strapped to both bumpers.
True, but it's really not so simple. JPEG's are non-redundant - delete one byte of data, and the whole file is unreadable. Over-the-air HD, however, is incredibly redundant. You can lose 40% of the data and still get a perfect picture. Lose 41%, though, and the picture drops out (numbers not exact).

Analog TV quality decreases fairly linearly. Digital TV quality stays constant long after analog TV looks like crap - but then it drops to nothing very sharply.
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  #5  
Old 10-24-2007, 08:23 PM
Keeve Keeve is offline
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I don't have HD, but the cable company signal is digital, and it happens to us too.
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  #6  
Old 10-24-2007, 08:26 PM
scm1001 scm1001 is offline
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Quote:
Originally Posted by Mr. Slant

If I were to delete 1K of data from a 100K JPEG file and then hand the JPEG to your computer, the picture wouldn't come out worth crap.

.
Is that true? If it was the last 1K of a progressive jpg then you would not really notice the difference. In a normal jpg you would just lose the picture after the loss. Only if it was the header information then the jpg would be useless.
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  #7  
Old 10-24-2007, 09:49 PM
Meeko Meeko is offline
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Quote:
Originally Posted by KneadToKnow
You don't say the source of your HD programming. If it's cable or satellite, my WAG would be that the bandwidth simply gagged. If it's over the air, I got nothin'.
Dish Network.

Uh......
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  #8  
Old 10-24-2007, 09:56 PM
GuanoLad GuanoLad is offline
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Quote:
Originally Posted by Meeko
Uh......
He means the signal quality dropped, and with digital signals there's a very (very) sharp dropoff between clear picture and no picture at all.

When a digital signal drops, you see the screen break up into squares and freeze or go black, rather than the familiar gradual noise buildup you get with the old analogue signals.
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  #9  
Old 10-25-2007, 08:56 AM
Max Torque Max Torque is online now
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If you have a DVR, and this happened while watching a recorded program, it's also possible that the hard drive is starting to fail; the picture and sound can sort of pixellate, "seize up", and refuse to play any more.
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  #10  
Old 10-25-2007, 09:45 AM
control-z control-z is offline
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Over the air digital works much the same, the picture is generally great or non-existent, with a small "crappy blocky mess" space in between.
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  #11  
Old 10-25-2007, 10:31 AM
Flander Flander is offline
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My experience with satellite tv is pretty crappy. Great picture unless there is a storm around. The picture will display artifacts or just black out. I live in south FL so this happens quite a bit. I will be going to digital cable very soon.
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